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Firth W, Robb JL, Stewart D, Pye KR, Bamford R, Oguro-Ando A, Beall C, Ellacott KLJ. Regulation of astrocyte metabolism by mitochondrial translocator protein 18kDa. bioRxiv 2023:2023.09.29.560159. [PMID: 37873215 PMCID: PMC10592862 DOI: 10.1101/2023.09.29.560159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The mitochondrial translocator protein 18kDa (TSPO) has been linked to a variety of functions from steroidogenesis to regulation of cellular metabolism and is an attractive therapeutic target for chronic CNS inflammation. Studies in the periphery using Leydig cells and hepatocytes, as well as work in microglia, indicate that the function of TSPO may vary between cells depending on their specialised roles. Astrocytes are critical for providing trophic and metabolic support in the brain as part of their role in maintaining brain homeostasis. Recent work has highlighted that TSPO expression increases in astrocytes under inflamed conditions and may drive astrocyte reactivity. However, relatively little is known about the role TSPO plays in regulating astrocyte metabolism and whether this protein is involved in immunometabolic processes in these cells. Using TSPO-deficient (TSPO-/-) mouse primary astrocytes in vitro (MPAs) and a human astrocytoma cell line (U373 cells), we performed metabolic flux analyses. We found that loss of TSPO reduced basal astrocyte respiration and increased the bioenergetic response to glucose reintroduction following glucopenia, while increasing fatty acid oxidation (FAO). Lactate production was significantly reduced in TSPO-/- astrocytes. Co-immunoprecipitation studies in U373 cells revealed that TSPO forms a complex with carnitine palmitoyltransferase 1a, which presents a mechanism wherein TSPO may regulate FAO in astrocytes. Compared to TSPO+/+ cells, inflammation induced by 3h lipopolysaccharide (LPS) stimulation of TSPO-/- MPAs revealed attenuated tumour necrosis factor release, which was enhanced in TSPO-/- MPAs at 24h LPS stimulation. Together these data suggest that while TSPO acts as a regulator of metabolic flexibility in astrocytes, loss of TSPO does not appear to modulate the metabolic response of astrocytes to inflammation, at least in response to the stimulus/time course used in this study.
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Affiliation(s)
- Wyn Firth
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Josephine L Robb
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Daisy Stewart
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Katherine R Pye
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Rosemary Bamford
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Asami Oguro-Ando
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Craig Beall
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Kate LJ Ellacott
- University of Exeter Medical School, Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
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Buckman LB, Anderson-Baucum EK, Hasty AH, Ellacott KLJ. Regulation of S100B in white adipose tissue by obesity in mice. Adipocyte 2014; 3:215-20. [PMID: 25068089 PMCID: PMC4110099 DOI: 10.4161/adip.28730] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 11/29/2022] Open
Abstract
S100B is a calcium binding protein found in adipose tissue; however, relatively little is known about the physiologic regulation or distribution of the protein within this organ. We examined plasma S100B concentration and white adipose tissue (WAT) s100b mRNA levels in lean and diet-induced obese (DIO) mice. Plasma S100B levels were increased by obesity. In WAT, s100b gene expression was also significantly increased by obesity and this increase was reversed following weight-loss. s100b gene expression was detected in both the adipocyte-enriched and stromal-vascular fractions of WAT; however, the increase in s100b gene expression in obese animals was only detected in the adipocyte-enriched fraction. Our results support published in vitro data indicating that WAT S100B may contribute to obesity-associated inflammation.
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